Health officials putting out a call for adults to get vaccinated with the U.S. on track to have its worst year for whooping cough in more than 50. Nearly 18,000 cases reported so far this year, more than twice last year’s total. Nine children have died this year according to the Centers for Disease Control and Prevention.

The highly contagious bacterial disease, also known as pertussis, which sounds like this:

(Coughing)

As children gasp for breath. Often passed on from adults.

Health officials saying it is especially important for pregnant woman to get vaccinated, so they don’t spread it to infants who are too young to get the vaccine.